The object of this study is to assess the impact of work stress on cardiac autonomic control. Written diaries and questionnaires will be used to measure work stress and the fit between an individual's vocational personality and perceptions of work climate. Cardiac autonomic control will be measured by ambulatory blood pressure monitoring. There are 3 levels of participation. One group participates for 1 day. In the morning, subjects complete questionnaires on work stress, vocational preference, and organizational climate. For the rest of the day they complete a brief diary each time they are signaled by a beeper-like device set to signal on average once every hour. The diary addresses current activities, time of day, and current mood. The second group and third group participates for 2 consecutive days. On Day 1, both groups receive a screening electrocardiagram and brief physical examination. Following this, ECG electrodes, a blood pressure monitor, and a respiration monitor will be attached and subjects will lie on a table for a brief period of time, after which they will engage in a two psychologically challenging tasks for 5 min each. After these tests, the table will be tilted to a 70 degree angle, with head upright, and remain in this position for another 15 minutes. These 2 groups also complete the same questionnaires and daily diary as the first group. On Day 2, subjects wear an ambulatory blood pressure monitor throughout the day during their normal activities. They also complete the diary when prompted by the reminder device, on an average of three times per hour. The second group returns to the Irving Center for Clincial Research where they wear the monitor through dinner and while watching a video. The third group stays overnight at the ICCR, where the blood pressure monitor remains on through the night until they awaken.